


Everything You Want to Understand

by SongbirdSilence



Category: Undertale (Video Game)
Genre: Body Worship, F/M, Fluff, Gender-Neutral Pronouns, Hurt/Comfort, M/M, Mild Language, Post-Pacifist Route, Reader-Insert, Romance, fondle dem bones, no spoopy skeledick, slight angst
Language: English
Status: Completed
Published: 2015-10-20
Updated: 2015-10-20
Packaged: 2018-04-27 06:08:29
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,820
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5036806
Author URL: https://archiveofourown.org/users/SongbirdSilence/pseuds/SongbirdSilence
Summary: <blockquote class="userstuff">
              <p>In which you want to get to know a certain skeleton while also being sexually attracted to him.</p>
            </blockquote>





	Everything You Want to Understand

**Author's Note:**

> Omg there are so many Sans/Reader fics, but I don't really give a shit.  
> Umm uh Sans is hard to write. ^^;; Fuuuuck me. So this was more of a dip-my-toes-in thing. I love the Undertail community, and the Sans/Reader fics I've read on this site are pretty great. XD  
>  **EDIT:** Okay, I initially wrote Sans's dialogue with correct grammar, but that's actually been bugging me more. ^^;; It's just weird to me. So I changed it.  
>  Might try writing some Papyrus/Reader soon, because the guy's so adorable that I really want to. Especially embarrassed Papyrus. Yesss.  
> Oh, and Mettaton. I want to write his character as well. And because EX is hot as hell.

_I really, really like Sans._

This realization came to you when you were doing nothing at all.

And that was just it—you _hate_ doing nothing. For one, it's boring, and giving yourself too much time to think had...different results. However, today, you don't mind leaving your brain to trail off on its own. Because no matter what your mind's tangents started as, it all eventually led to one skeleton. Thoughts of him, of some bad jokes you could say to him, remembering that one time he literally crashed into Toriel's computer trying to do...something, and anything else, you envisioned.

The weird feeling that resides in your chest further cemented the fact. You sigh.

You don't even remember when you met the skeleton brothers. They just...showed up one day in your town, along with their other eccentric companions. While you like Toriel, Undyne, Alphys, and all of them, you always got along with Sans and Papyrus the best. Days were spent going to the Grillby's that had opened up in town and watching Mettaton's show on TV, and it was pretty great.

Being friends with them is a "special" experience, made humorous ("dontcha mean humerus?" you imagined Sans quipping in response.) by the stark contrast between the two. Papyrus's childlike excitement and zeal made you laugh. It's never awkward with him around, even if he can be overbearing at times.

And Sans?

He's mostly a chill dude. Lazy and an (in)famous pun-lover, Sans is friendly in a calmer way than Papyrus is. He's the kind of guy who can summon endless wit, and he's the only one you can have comfortable silences with. That being said, Sans is perhaps _too_ mysterious. There are times where he's eerily solemn, maybe even borderline dark. He pops in and out like it's nothing, is more observant than people give him credit for, dodges questions, and had that tired, tired expression when he thought nobody was looking.

All the while wearing that same skeleton grin.

Yeah. You like him. A lot. You like his easygoing nature, his terrible puns, that look he gives you that makes you think, _Fuck he's a skeleton but he's so attractive._

Even then, it's frustrating sometimes. You've been friends with him for a long time now; it's disconcerting to know that you have absolutely no idea what goes through his head.

You did ask him about it one time.

"don't think anything could be going through my head." Sans knocked his phalanges against his skull, producing a hollow sound. "careful, some skeletons get touchy about their lack of brain." He winked as you reluctantly laughed at the joke, and nothing else was said about it.

Maybe you were overthinking this. Maybe you were confused. That wide, distracting smile he wore when you laughed at his jokes didn't seem to help, in any case.

Maybe it was just the fact that your heart began skipping too many beats around him added to the frustration.

Admittedly, it's more than one type of frustration, if you're being honest with yourself. Hell, you've even been looking at a skeleton diagram, out of curiosity. You'd trace your own features where the bones would be and call out their names. You'd wonder what it would be like to see a different kind of grin, a different kind of way you'd touch his bones, and you'd begin to imagine and picture things before cutting off the thoughts in shame.

Frustration often breeds action.

So, of course, when you two were alone in their house, it would have ended up like this.

You and Sans are on the couch watching a random soap opera, mostly so the both of you can make fun of it. It's been a relaxing Saturday so far; Papyrus was out doing something with Undyne, and while you were invited to tag along, you opted not to. Sans was off from work that day, so the two of you ended up hanging out.

Just from a quick glance you can tell that Sans is kind of zoning out. You can't really blame him, because the soap had reached a dull point. You're surprised that you can read his features so easily now. It's his eye sockets and body language you look for. Like how tense his bones are, and how his face features angle say a lot.

Suddenly, you become aware of how much you've been ogling at him, and naturally it's that exact moment when he notices.

"uh, something on your mind, kid?"

 _Why am I so obvious?_ Your face warms up as you avert your gaze, and you curse mentally. Honestly, you can't be bothered to make up an excuse. You know he wouldn't buy it.

And while you weren't usually one for spur-of-the-moment decisions...

_I suppose now is a good time as any._

"Um, I... Can I tell you something?"

"shoot."

You touch the arm of his jacket, breathing deeply.

"I...I like you. I mean, I like you more than a friend, Sans."

The silence is unnerving. You don't really want to look at his face, so you keep your eyes fixed onto the ground. _What is he even going to say to this?_ Sans is the last person you expect to be interested in a relationship. He's never brought up the subject of romance unless Undyne and Alphys were topics of the conversation. Just springing this onto him seems silly, now that you think about it.

_Ugh. There's no taking it back now, I guess._

Your heartbeat is so intense that you're afraid of his response drowning in the noise, but you catch it anyway.

"heh. got a bone fetish or somethin'?"

...and now you wish you hadn't.

You glare at him, vexed at what seemed to be a brush-off. "Sans, I hope you fucking know you are _not_ just a fetish to me."

You almost expect him to be surprised, but of course he's not. It's Sans. If he was, there were no signs of it. He only shrugs, his stare becoming half-lidded. His face bones look sunken.

You realize it's that tired look again, but it's the first time you've seen it directed at a person.

"sorry to say, there's not much here for ya. just some old bones." His smile is half-hearted.

"That's not true!" you nearly shout. Before you know it, you find your head buried into his jacket and your arms capturing him. "I mean, I... I can't say I love you, because I don't really know you. But I want to know you. Every day I spend with you, it just feels like there's something more with you. Something you can't tell anyone. You can tell me I'm wrong, or that you don't want to say anything right now, or that you don't want to say anything ever, but... I want you to know that you can come to me. I don't care if it's four in the morning or if I'm in the shower or some shit." You chuckle weakly. "So, um, I can be your comfort, if you want."

You lift your head up, partly because you want to see him, and partly because you don't know how to continue.

Still grinning, still tired, but hurting. He looks like he's literally going to pass out at any second, like something's been drying up in him and shriveling for a very, very long time. It's something you've never seen on him before, but you know exactly what it is.

It's everything you can't understand about him.

He shrugs again somehow more sluggishly than before.

"you don't know what you're asking for, kid." It almost sounds like a threat, but that expression says otherwise.

"Sans, that doesn't matter to me. I want to do this for you."

You press your cheek against the side of his skull, still embracing him. The sensation cools your face. You wonder how he's feeling right now. He would have pushed you off already if he disliked this.

_Right?_

But even then, he's not hugging you back. His arms are just hanging slackened at his sides.

After staying like that for a while, Sans pulls away. Immediately you notice something, and it startles you.

_Something's wrong._

"hey, that's not everything, is it? leaving me out of the loop's kinda..."

The small points of light that served as his eyes are gone. There's only pitch blackness in his eye sockets. You have the feeling that you've done something terribly wrong.

"...rude."

Yet...there's this familiar heat that shoots through you, and even though you're scared, it's bothering you. You take in the situation even though you're not trying to: he's centimeters away. His bones are so close to you.

Too close.

"be straight with me."

There's nothing that can stop your previous fantasies from arising again. Images flash as you, panicked, try to dismiss them all.

_But he's giving you that look and it's paralyzing._

"Huh?"

"what else's been going on in there?"

"I..."

"don't know what i'm talking about?"

 _I do, but I don't know how to say it without seeming like a total creep_. It's taking all of your willpower to not grumble in exasperation. _Oh, wait, maybe that's because I am one!_

"i'll give you a hint: i saw something on your phone." You remembered lending it to him when he had to call Papyrus the other day. "it was, uh, a diagram of a skeleton."

You freeze. You had left your browser open. _Shit. Shit._

His face leans in more. "your heart's beating pretty fast right now. what's eating at you when i'm this close?"

"Ah..." You can't tear your eyes or your body away from him, even though you're mortified. It occurs to you how hypocritical Sans is being: he's demanding answers from you, while he remains closed up as ever.

"tell me." His tone is deep and casual as ever. Another burst of warmth inflames you, but you shudder as if feeling the opposite.

It's his stares. His voice. His banter. His careless attitude. His slight changes in expression that said so much. There was this part of you that wanted to make sure he didn't look at anybody else, to hear no words but all kinds of sounds come from him, and make those changes in expression major, erratic, and pleasured. That voice is hollering right about now, tempting and ushering you. And how again are you supposed to tell him this?

Bottling up. Longing. Noise in your head.

Finally, hoping that all of this heat would just release by doing this, you blurt out, "I'm seriously tempted to jump your bones right now."

You're burning and your throat feels like the aftermath of a gust of desert wind, but you keep your gaze steady and hard as you look into his eye sockets. Your grip on him tightens. You don't break eye contact for a second, and neither does he. Seconds that feel like days pass.

And then...

The lights reappear in his eyes.

Sans starts chuckling. 

"eh...heheh..."

Little trickles of amusement turn into waterfalls of complete and utter laughter. It's the hardest you've ever seen him laughing. You have no idea what look is on your face right now.

...

...He's _still_ going.

You're silent in—well, what? Anger? Fear? Bewilderment? But the first thing that comes to your mind is, _He's laughing and it's pissing me off because it makes me want to laugh too and what the hell is he thinking._ So you settle for anger.

"... _What?_ " you snap, and you swear your eyes are steel knives at this point.

"you said...'jump your bones.' that's—that's the best."

 _How is he laughing harder?_ But the irritation has fallen off of your face: eyebrows unknit as your mouth hangs open very slightly. You close your mouth.

And then you join in, because it's hilarious how the tension has just been pushed aside. Because this conversation is ridiculous. Because seriously, how did you not catch yourself saying this. You laugh because he's laughing. Just laughing, and laughing, and laughing, and god your sides hurt so much. Somewhere in that period of time you acknowledge in your mind that your reaction is irrational, but you don't care.

After a while, it starts dying into tiny giggles, and it fades into broad smiles. You look at each other and you love how happy he is right now. It's the first thing about him you've fallen in love with.

That's when you kiss him.

You close the gap, place your lips on his teeth, and even though it's more of a press than a kiss, it sends tingles up your spine.

You find yourself on top of Sans, him leaning his back against the couch as you start to straddle him. You tell him to take off his jacket and shirt, and he complies. Only his shorts are left on. There's enough exposed for you to do your job, anyway.

You slither one hand inside his shorts and set it on the edge of his pelvis, the other hand only having a finger pointing at where his forehead would be. "Skull." He watches you as you move down and trace his jawline. "Mandible." Further down. "Cervical vertebrae." Down and across. "Clavicle." Eye sockets close, a quiet sigh arising in satisfaction. You label his arm, afterward starting again at his torso.

When you stroke his sternum and ribs, that's when he starts getting a bit louder. He moans lightly as you apply different types of pressure, and you can't stop yourself from smirking. It's so unlike him.

"Just let it out," you murmur, finally coming down to his pelvis and pressing down. 

"...enjoying this, huh?" Sans's voice sounds strained, but he still manages a cheeky look.

You nod. This time, you switch gears and shift your body so you can start near the bottom of his fibula and work your way up. Your body dips to the point where you're basically lying on top of him. As you caress his femur, you hear him inhale distinctly.

"mnnn. that's nice."

Then, without warning, you bring up your hands to grip the sides of his rib cage. He twitches at the sudden change of force, but that's all the time you give him to react. You start grinding roughly on his pelvis, moving your left knee up to rub against the bottom of his ischium. He reaches up to grasp your legs while trying to add his own movements, increasing the friction.

Sans shudders in ecstasy, letting out a baritone rumble. You savor the sound of it, deciding that you'd like more of this from him.

You stick your tongue out and lap at his clavicle, and...

That look on his face is divine. His face is contorted in bliss, he's sweating, producing sounds, and he's so fucking irresistible it hurts. You don't even recall what happens after this thought. It's a mess of touching, tasting, grazing teeth against bones, kissing, licking, sucking, and whatever else you don't remember doing but did anyway.

Sans's bones are rattling until you're almost worried that he would come undone like a puzzle.

"aaah—fuck, that's goooood. nngh—!" 

He convulses fiercely, tensing up as he grips your thighs. He lets out incoherent noises, and the way he's trying to hold them back is adorable. You keep touching him as he starts to climax, but gradually let go to watch and appreciate his current state. Promptly afterward, he becomes limp, and his bones sink into the couch as if they were 20-pound weights.

You smile, getting off and lying beside Sans. Snaking an arm around him, you ask, "How're you feeling?"

He sighs, somehow slouching even lower into the couch. "...shit. how did you do that?"

"Um, I kind of followed my instinct?" You legitimately don't know where that came from. "It just...happened."

There's a brief moment of silence.

"So, what was with that, anyway?" you question. "I'm hugging you one moment, and the next you demand to know about my..." _I'm not even going to try and phrase that correctly._ "...you know?"

He pauses in thought before answering, "well, it was a test."

"I...what?"

"you wanted me to be upfront with you. so ya had to show me you could do the same." Sans look you in the eyes. "if we're doing this, you gotta be honest with me too, bone-jumping urges and all."

You feel embarrassed once again, puffing up your cheeks. He looks amused.

"You still haven't told me anything."

"mm. maybe next time. too tired now, tibia honest." Sans winks, and you groan in frustration.

"Lazy." You kiss him again, and when you part, you're only about an inch away. "Promise you'll tell me sometime?"

"normally don't like making promises: not really my thing." He stretches. "but...welp. it's not like i can say no to you now, eh?"


End file.
